The prior methods and apparatus for forming manufacturing lenses such as contact lenses can be less than ideal in at least some respects. For example, contact lenses with internal fluidic structures such as chambers can be challenging to manufacture in at least some instances. Although structures such as balloons or modules can be embedded within contact lenses, such structures can make the manufacturing process somewhat more involved than would be ideal.
Multifocal contact lenses may be of two types of designs: those which provide simultaneous vision (U.S. Pat. Nos. 7,517,084, 7,322,695, both by Wooley, et al) and those that provide alternating vision (U.S. Pat. Nos. 7,503,652, 6,092,899, 7,810,925, by Evans, et al). Both types of contact lenses may have at least two or more optical zones of different focal lengths. Simultaneous vision can be provided by multifocal contact lenses that have optical zones of different focusing power disposed radially symmetrically about the optical center of the lens which is also frequently its geometrical center. Alternating vision can be provided by designs in which the optical zones are separated from each other, typically along the vertical meridian, so that the optical center of each zone comes in alignment with the pupillary center as the lens is translated upwards during downward gaze. Neither approach is well accepted by wearers of contact lenses, and there is a continuing unmet need for an accommodating contact lens with a dynamically variable optic that has a single variable focal length, which is easily worn and used. The image quality provided by an accommodating contact lens that can be easily adjusted by the wearer should be much better than multifocal lenses.
A prior contact lens design has been described by Iuliano (U.S. Pat. No. 7,699,464 B2). The manufacture of such a device can be more complicated than would be ideal. Earlier, Elie disclosed an accommodating contact lens (WO 1991010154 A1).
Accommodating contact lenses have been proposed in which a central chamber increases curvature when an eyelid engages a lower chamber coupled to the central chamber. The prior lenses may have less than ideal optical performance, and can be more difficult to use and manufacture than would be ideal. In some instances, the prior contact lenses may provide less than ideal responses to eyelid pressure, and may not change shape in response to eyelid pressure as readily as would be ideal. Also, portions of the lens can be formed in stages and different pieces brought together to form the lens, which results in additional steps in the manufacturing process. Although modules embedded in accommodating contact lenses can be effective, such modules can result in greater complexity and cost than would be ideal. Also, embedded modules may provide non-ideal amounts of resistance to movement of the structures of an accommodating contact lens, depending upon the stiffness of the tensile modulus of the membrane comprising the module.
In light of the above, improved contact lenses and methods of manufacture are needed. Ideally, such contact lenses and methods of manufacture would provide contact lenses that change shape with decreased amounts of pressure, involve fewer steps and allow contact lenses to be produced in large quantities with internal cavity structures.